This invention relates to a system or apparatus for mixing and delivering a two-part polymer material to various locations of a human body. In particular, the present invention provides a system that allows for ethylene-oxide sterilization of pre-packaged polymer components that are mixed when extruded from a syringe delivery system.
In many orthopedic or reconstructive surgical procedures it is common to use polymer based adhesives, cements or spatial fill materials to either attach implants or artificial joints to bones or joint structures or to fill cavities in a persons soft tissue or soft tissue supporting structures to achieve a desired reconstructive result. These adhesives or fill materials are typically formed in place by co-extruding a base material and a second material that may contain appropriate catalysts and the like, intermixing the materials so that when they are extruded into position they begin to cure into the final, hardened material.
In some prior art systems, the material are mixed in a separate mixing vessel and then loaded into an extrusion device. This process is disadvantageous because such mixing and loading typically exposes an operator to an offensive odor, is time consuming and may be messy. Additionally, the component materials may be difficult to handle.
Another problem with such a prior art system is that the mixing processing results in air being included into the adhesive. Since such entrapped air may reduce the performance of the adhesive or filling material, it must be removed prior to use. Typically air is removed from the mixture by applying a vacuum to the mixture, or by mixing the two components of the final material under a vacuum. This requires additional equipment, which may preclude mixture of the components in a location convenient to use of the material.
One solution to these problems has been to develop a double barrel syringe system with each component pre-packaged in its individual barrel. When the plunger of the system is activated, both of the materials are co-extruded through a mixing nozzle, the specifications of which may be precisely engineered to deliver a properly mixed material at the use end of the nozzle. In this way the two components may be packaged in a single unit, de-aired, and be ready for use. Another advantage of such a system is that final material may be prepared in a desired amount. If more material is needed, a second, third and so forth syringe assembly may be used.
While such two barreled systems have been shown to be quite useful in many applications, sterilization of the component materials of such system has been problematic because the components may be damaged by the method used to sterilize the system. For example, while dry heat may be acceptable, high temperatures and long sterilization cycles can damage not only the polymer components, but also the delivery system and its packaging. Steam sterilization is also unsuitable because steam does not easily pass in and out of a closed system and the packaging and delivery system may not be capable of withstanding the high temperatures without chemical and/or physical damage.
High energy radiation, such as gamma radiation or e-beam sterilization are not suitable because the energy of these methods imparted into the polymer components may cause crosslinking or gelling of the component materials during the sterilization process are typically heat sensitive and thus can be degraded if heat sterilized. Additionally, gas sterilization, such as with ethylene oxide, has been problematic because the materials used to form the barrel and plungers of the syringe system have not been sufficiently permeable to the gas to allow transmission of the gas into the components to adequately sterilize them. Sterilization of components by filtering the components prior to adding the components to the syringe barrel has been found to provide a sterile product, but is expensive and requires special clean-rooms and expensive control methods to ensure sterility.
What has been needed, and heretofore unavailable, is an inexpensive syringe system designed from mixing and delivery of two part polymer systems that may also be gas sterilized, thus eliminating the need for pre-sterilization or aseptic packing, or a second sterilization step after the syringe is placed in its final packaging. Such a system would also be advantageous in that a filled two-part syringe assembly could be simply placed into a bag, tray, box or kit and sealed into a gas permeable pouch made from a material such as Tyvek and sterilized. The present invention fills these, and other needs.